JP7463875B2 - Optical laminate, and polarizing plate, display panel, and image display device using the same - Google Patents

Description

The present invention relates to an optical laminate, and a polarizing plate, a display panel, and an image display device using the same.

As an optical film applied to image display devices, etc., there is an optical laminate that imparts a desired phase difference to incident light. For example, a circular polarizing plate that combines a λ/4 phase difference layer and a linear polarizing plate is used to prevent reflection in image display devices.

It is well known that such optical stacks do not provide equal effectiveness at all wavelengths.
For example, a circular polarizing plate formed by laminating a λ/4 retardation layer and a linear polarizing plate can circularly polarize light of a wavelength of 550 nm and significantly suppress external light reflection, but light of wavelengths longer and shorter than 550 nm becomes elliptically polarized light, resulting in a problem of reduced anti-reflection function.
As a method for solving this problem, a method has been proposed in which the retardation layer of the circular polarizer is a combination of a λ/4 retardation layer and a λ/2 retardation layer.

However, image display devices having positive A layers such as a λ/4 retardation layer and a λ/2 retardation layer have a problem in that display quality (for example, contrast) is degraded when viewed from an oblique direction.
For this reason, an optical laminate comprising a combination of a positive A layer and a positive C layer has been proposed (Patent Documents 1 and 2).

JP 2006-215221 A JP 2016-4142 A

In Patent Document 1, a layer in which the liquid crystal composition is oriented in-plane on the substrate and a layer in which the liquid crystal composition is oriented vertically on the substrate must be prepared, and these layers must be peeled off from the substrate and laminated. For this reason, the optical laminate in Patent Document 1 has the problem that the process becomes complicated. In addition, in Patent Document 1, the positive A layer and the positive C layer are laminated via an adhesive layer or pressure-sensitive adhesive layer, so the thickness increases by the amount of the adhesive layer or pressure-sensitive adhesive layer, which hinders thinning.

In Patent Document 2, the positive A layer and the positive C layer are directly laminated without an adhesive or pressure-sensitive adhesive layer therebetween, which can solve the problem of thinning.
However, when the optical laminate of Patent Document 2 was attached to another member, there were many cases where the positive A layer and the positive C layer peeled off at the interface. Also, among the optical laminates of Patent Document 2, in an embodiment in which the positive C layer and the positive A layer are formed on a peelable substrate and the positive C layer and the positive A layer are transferred to another member, there were many cases where the positive A layer and the positive C layer peeled off during transfer.

The present invention aims to provide an optical laminate that is formed by directly laminating an alignment layer, such as a positive C layer, and a positive A layer and has excellent adhesion between the alignment layer and the positive A layer, as well as a display panel and an image display device that use the same.

The present invention provides the following [1] to [4].
[1] An optical laminate having an alignment layer and a positive A layer, the alignment layer and the positive A layer being in contact with each other, the positive A layer containing a compound a, the alignment layer containing the compound a transferred from the positive A layer and other compounds, the compound a containing an atom X that is substantially not contained in the other compounds, and when the average detected amount of the atom X in the positive A layer is standardized to 100 on a mass basis, the average detected amount of the atom X in the alignment layer is 23 or more.
[2] A polarizing plate having a polarizer, a transparent protective plate A arranged on one side of the polarizer, and a transparent protective plate B arranged on the other side of the polarizer, wherein either the transparent protective plate A or the transparent protective plate B is the optical laminate described in [1].
[3] A display panel comprising the optical laminate according to [1] above disposed on a light exit surface of a display element.
[4] An image display device comprising the display panel according to [3] above.

According to the optical laminate of the present invention, and the display panel and image display device using the same, the alignment layer and the positive A layer are directly laminated, so that the optical laminate can be made thin, and the alignment layer and the positive A layer have excellent adhesion to each other, so that the workability and stability over time can be improved.

1 is a cross-sectional view showing one embodiment of an optical laminate of the present invention. 1 is a cross-sectional view showing one embodiment of a polarizing plate of the present invention. 1 is a cross-sectional view showing an embodiment of a display panel of the present invention.

Hereinafter, an embodiment of the present invention will be described.
In this specification, the expression "AA to BB" means "at least AA and at most BB."

In addition, in this specification, "in-plane retardation at a wavelength of 450 nm" may be expressed as "Re(450)", "in-plane retardation at a wavelength of 550 nm" may be expressed as "Re(550)", "in-plane retardation at a wavelength of 650 nm" may be expressed as "Re(650)", and "retardation in the thickness direction at a wavelength of 550 nm" may be expressed as " Rth (550)".
The in-plane retardation (Re) and the retardation in the thickness direction (Rth) can be calculated from Nx, Ny, Nz and the thickness d (nm) of the retardation layer by the following formula.
In-plane retardation (Re) = (Nx - Ny) x d
Retardation in the thickness direction (Rth) = ((Nx + Ny) / 2 - Nz) x d

In addition, in this specification, a positive A layer is a layer that satisfies the relationship Nx>Ny≒Nz, where Nx is the refractive index in the X-axis direction, which is the axial direction along the plane of the layer that has the highest refractive index, Ny is the refractive index in the Y-axis direction along the plane of the layer that is perpendicular to the X-axis, and Nz is the refractive index in the thickness direction of the layer.In addition, in this specification, a positive C layer is a layer that satisfies the relationship Nx≒Ny<Nz.

[Optical laminate]
The optical laminate of the present invention comprises an alignment layer and a positive A layer, the alignment layer and the positive A layer being in contact with each other, the positive A layer contains a compound a, and the alignment layer contains the compound a transferred from the positive A layer and other compounds,
The compound a contains an atom X that is not substantially contained in the other compounds,
When the average detectable amount of the X atoms in the positive A layer is standardized to 100 on a mass basis, the average detectable amount of the X atoms in the alignment layer is 23 or more.

FIG. 1 is a cross-sectional view showing an embodiment of an optical laminate of the present invention.
The optical laminate 100 in Fig. 1 has an alignment layer 20 and a positive A layer 30, and the alignment layer 20 and the positive A layer 30 are in contact with each other. In addition, in the optical laminate in Fig. 1, the alignment layer 20 and the positive A layer 30 are formed on a substrate 10.

The optical laminate of the present invention has an alignment layer and a positive A layer, and the alignment layer and the positive A layer are in contact with each other. In this way, the alignment layer and the positive A layer of the optical laminate of the present invention are directly laminated without an adhesive layer or the like, so that the optical laminate can be made thin and can be easily manufactured.

<Average detected amount of X atoms in the alignment layer>
The optical layered body of the present invention is required to have the following configurations (1) to (3), and the average detectable amount of atoms X in the alignment layer must satisfy the following condition (4).
(1) The positive A layer contains compound a.
(2) The alignment layer contains the compound a transferred from the positive A layer and other compounds.
(3) The compound a contains an atom X which is not substantially contained in the other compounds.
(4) When the average detectable amount of the X atoms in the positive A layer is normalized to 100 on a mass basis, the average detectable amount of the X atoms in the alignment layer is 23 or more.

Compound a means a liquid crystal compound contained in the positive layer A. Examples of the atom X contained in compound a include a sulfur atom and a nitrogen atom.
The other compounds refer to all compounds constituting the alignment layer except for compound a.
In this specification, the average detection amount in (4) above may be referred to as the "average detection amount of the alignment layer."

The average detection amount of the alignment layer satisfying the above condition (4) means that the compound a of the positive A layer has penetrated into the alignment layer in excess of a predetermined ratio. In this way, when the compound a of the positive A layer has penetrated into the alignment layer in excess of a predetermined ratio, the affinity between the positive A layer and the alignment layer increases and an anchoring effect occurs. Therefore, the optical laminate of the present invention having the above configurations (1) to (3) and satisfying the above condition (4) can improve the adhesion between the positive A layer and the alignment layer.
On the other hand, an optical laminate that does not satisfy the above condition (4) cannot achieve good adhesion between the positive A layer and the alignment layer, and peeling occurs at the interface between the positive A layer and the alignment layer due to stress generated during operations such as lamination and transfer.

The average detectable amount of the alignment layer is preferably 27 or more, more preferably 30 or more, and even more preferably 33 or more.
The more the average detection amount of the alignment layer is increased, the more gradually the adhesion improves, but there is a limit to the improvement of adhesion. In addition, since compound a penetrates into the gaps of the alignment structure of the alignment layer, the alignment of the alignment layer is not easily affected by compound a that has penetrated into the alignment layer. However, if the average detection amount of the alignment layer is too large, the positive A layer may become difficult to align, or problems may occur due to changes in the physical properties of the alignment layer. For this reason, the average detection amount is preferably 60 or less, more preferably 50 or less, and even more preferably 40 or less.

The average detection amount of the alignment layer can be increased or decreased by, for example, the molecular weight of the compound a in the positive A layer, the affinity between the alignment layer and the positive A layer, the solvent of the coating liquid for forming the positive A layer, etc. Specifically, the smaller the molecular weight of the compound a, the greater the average detection amount, and the greater the molecular weight of the compound a, the smaller the average detection amount. In addition, the higher the affinity between the alignment layer and the positive A layer, the greater the average detection amount, and the lower the affinity, the smaller the average detection amount. In addition, the higher the permeability of the solvent of the coating liquid for forming the positive A layer into the alignment layer, the greater the average detection amount, and the lower the permeability of the solvent into the alignment layer, the smaller the average detection amount. In addition, the higher the mass ratio of the solvent in the coating liquid for forming the positive A layer, the greater the average detection amount, and the lower the mass ratio of the solvent in the coating liquid, the smaller the average detection amount (mass ratio of the solvent in the coating liquid ≒ total amount of coating liquid - mass ratio of the solid content of the coating liquid).
In addition, as described later, when a specific liquid crystal compound is used as a compound constituting an alignment layer such as a positive C layer, and compound a is a compound containing a sulfur atom, the average detection amount can be easily increased. In addition, as described later, when compound a has a molecular structure that is easily movable, the average detection amount can be easily increased.

The mass-based detection amount of the atom X in the positive A layer and the alignment layer can be measured by preparing a measurement sample of a thin slice cut vertically into the optical laminate and measuring the cross-sectional side of the sample using a scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX). It is preferable to prepare 20 measurement samples and use the average values of the 20 measurements as various parameters related to the detection amount of the atom X.
The sample for measuring the thin section can be prepared, for example, by cutting the optical laminate to a predetermined size to prepare a cut sample, and then cutting the cut sample vertically with a diamond knife. The thickness of the sample for measuring the thin section is preferably 40 nm to 160 nm.

When measuring with an SEM-EDX analyzer, it is preferable to obtain a characteristic X-ray spectrum by adjusting the irradiation current and measurement time appropriately to ensure that the target element is sufficiently detected, in accordance with the quantitative conditions specific to each device (for example, for the SEM "SU8000" manufactured by Hitachi High-Technologies and the EDX "XMAX80" manufactured by Oxford Instruments, the acceleration voltage is 30 kV, the focal length is 15 mm, and the sample tilt is 0 degrees). In addition, the concentration of each element can be determined by the ZAF correction method (a method in which the content of each element is determined by applying atomic number correction Z, absorption correction A, and fluorescence correction F to the relative intensity of each element).

In this specification, the above-mentioned measurements regarding the amount of detected X atoms, as well as other measurements and evaluations, are performed in an atmosphere with a temperature of 23°C ± 5°C and a humidity of 40% to 65%, unless otherwise specified. Furthermore, the sample is exposed to the above atmosphere for 30 minutes or more before the measurements and evaluations.

<Coefficient of variation of detection amount, variation ratio>
In the optical laminate of the present invention, it is preferable that the detected amount of the atom X in the alignment layer satisfies the following condition 1.
(Condition 1)
The amount of the atom X in the alignment layer is detected at 100 points every 26 nm in a direction parallel to the interface at a position 200 nm in the thickness direction from the interface between the alignment layer and the positive A layer. The mass-based coefficient of variation of the amount of the atom X detected at the 100 points is 0.16 or more.

Satisfying condition 1 means that the amount of compound A permeated into the alignment layer varies from place to place in the alignment layer, and the degree of variation is greater than or equal to a predetermined value. In this way, by varying the permeability of compound A from place to place in the alignment layer, the adhesion between the alignment layer and the positive A layer can be improved.
The coefficient of variation in condition 1 is preferably 0.20 or more, and more preferably 0.25 or more.
From the viewpoint of suppressing variations in physical properties in fine regions, the upper limit of the coefficient of variation in Condition 1 is preferably 0.60 or less, more preferably 0.50 or less, even more preferably 0.40 or less, and even more preferably 0.35 or less.
The coefficient of variation is a dimensionless parameter obtained by dividing the standard deviation (variation) by the average value.

In the optical laminate of the present invention, it is preferable that the detected amount of the atom X in the positive A layer and the alignment layer satisfies the following condition 2.
(Condition 2)
The amount of the atom X in the positive A layer is detected at 100 points every 26 nm in a direction parallel to the interface at a position 200 nm in the thickness direction from the interface between the positive A layer and the alignment layer. The mass-based coefficient of variation of the detected atom X is defined as CV1.
The amount of the atom X in the alignment layer is detected at 100 points every 26 nm in a direction parallel to the interface at a position 200 nm in the thickness direction from the interface between the alignment layer and the positive A layer. The mass-based coefficient of variation of the detected atom X is defined as CV2.
The ratio of the CV1 to the CV2 (CV2/CV1) is 2.00 or more.

Satisfying condition 2 means that the amount of compound A permeated into the alignment layer varies from place to place in the alignment layer, and the degree of variation is equal to or greater than a predetermined level, as in condition 1. In this way, by varying the permeability of compound A from place to place in the alignment layer, the adhesion between the alignment layer and the positive A layer can be improved.
The ratio in condition 2 is preferably 2.10 or more, and more preferably 2.20 or more.
The upper limit of the ratio in Condition 2 is preferably 4.00 or less, more preferably 3.00 or less, and even more preferably 2.50 or less, from the viewpoint of suppressing fluctuations in physical properties in the fine regions.

Conditions 1 and 2 can be adjusted, for example, by the in-plane uniformity of the orientation degree of the orientation layer. Specifically, the lower the in-plane uniformity of the orientation degree of the orientation layer, the larger the coefficient of variation of condition 1 and the ratio of condition 2 tend to be, and the higher the in-plane uniformity of the orientation degree of the orientation layer, the smaller the coefficient of variation of condition 1 and the ratio of condition 2 tend to be.

<Orientation Layer>
The alignment layer is disposed at a position in contact with the positive A layer in the thickness direction of the optical laminate.
When an alignment layer and a positive A layer are formed on a substrate, it is preferred that the alignment layer is first formed on the substrate, and then the positive A layer is formed.

The alignment layer contains compound a transferred from the positive A layer and other compounds. The other compounds are all compounds excluding compound a from the compounds constituting the alignment layer. The main component of the other compounds is a liquid crystal compound, and the liquid crystal compound is preferably a liquid crystal compound having a photosensitive group.
The other compounds are those that do not substantially contain the atom X contained in the compound a. In this specification, "the other compounds do not substantially contain the atom X" means that the other compounds contain 0.1% by mass or less, more preferably 0.01% by mass or less, of the total amount of the other compounds.

The alignment layer may be, for example, a homeotropic alignment layer.
The homeotropic alignment refers to a state in which liquid crystal compounds are aligned parallel and uniformly to the normal direction of the layer, that is, a state in which they are aligned vertically.
A typical example of a homeotropic alignment layer is a positive C layer. That is, the alignment layer may be a positive C layer.
Hereinafter, an embodiment of a positive C layer, which is a typical example of an alignment layer, will be mainly described.

The liquid crystal compound of the positive C layer may be a material made of a liquid crystal polymer or a material made of a liquid crystal monomer.
The liquid crystal compound of the positive C layer is preferably a liquid crystal compound having a photosensitive group from the viewpoint of the alignment of the positive A layer formed on the positive C layer. That is, the alignment layer preferably contains a liquid crystal compound having a photosensitive group as another compound.

In this specification, a photosensitive group refers to a functional group that bonds with other molecules when irradiated with light. In addition, in this specification, a liquid crystal compound refers to a material that exhibits liquid crystallinity when the material alone is subjected to a physical external stimulus (such as heating, cooling, application of an electric field, a magnetic field, or shear), or that exhibits liquid crystallinity when mixed with a solvent or a non-liquid crystal component.

Examples of the liquid crystal compound having a photosensitive group include a photosensitive side-chain type liquid crystal polymer having a side chain containing a structure in which the following (i) and (ii) are bonded with or without a spacer. As the liquid crystal compound having such a photosensitive group, those described in JP2016-4142A can also be used.
(i) Photosensitive groups such as a cinnamoyl group, a chalcone group, a cinnamylidene group, a biphenylacryloyl group, a furylacryloyl group, a naphthylacryloyl group (or a derivative thereof).
(ii) Substituents such as biphenyl, terphenyl, phenylbenzoate, and azobenzene, which are often used as mesogenic components of liquid crystal polymers.

Examples of the photosensitive side chain type liquid crystalline polymer include a polymer which has a photosensitive side chain having a carboxyl group at the side chain terminal, forms a rigid structure by dimerization through hydrogen bonding of the carboxyl group at the side chain terminal, and exhibits liquid crystallinity without including a mesogenic group in the structure of the side chain itself.
Examples of the main chain constituting the photosensitive side-chain type liquid crystal polymer include hydrocarbons, acrylates, methacrylates, siloxanes, maleimides, and N-phenylmaleimides, to which the above-mentioned side chains are bonded via a spacer. These polymers may be either single polymers consisting of the same repeating units, copolymers consisting of a plurality of units having side chains with different structures, or copolymers obtained by blending units having side chains containing photosensitive groups with units having side chains not containing photosensitive groups to an extent that does not impair liquid crystallinity. In addition, a low molecular weight compound may be added to enhance the alignment.

The photosensitive side-chain liquid crystal polymer may be a polymer in which a crosslinked structure is introduced using a crosslinking agent such as an isocyanate material or an epoxy material, for the purpose of improving heat resistance, etc.

The photosensitive side-chain type liquid crystal polymer is preferably a polymer formed using a monomer having a side chain represented by the following general formulas (1) to (3).
In addition, polymers formed using monomers having side chains represented by the following general formulas (1) to (3) have high affinity with compounds containing sulfur atoms. That is, when an alignment layer such as a positive C layer contains a polymer formed using a monomer having a side chain represented by the following general formulas (1) to (3) and compound a in a positive A layer contains a sulfur atom, compound a is more likely to penetrate into the positive C layer, which is preferable in that the amount of atom X (e.g., sulfur) detected is more likely to satisfy the above range.

In each of Chemical Formula 1 and Chemical Formula 2, n is an integer of 1 to 12, m is an integer of 1 to 12, X or Y is none, -COO, -OCO-, -N=N-, -C=C- or _-C6H4- , _W1 is a cinnamoyl group, a chalcone group, a cinnamylidene group, a biphenylacryloyl group, a _{furylacryloyl} group, a naphthylacryloyl group or a derivative thereof, or is -H, -OH or -CN, and _W2 is a cinnamoyl group, a chalcone group, a cinnamylidene group, a biphenylacryloyl group, a furylacryloyl group, a naphthylacryloyl group or a derivative thereof, or is -H, -OH or -CN. In each of general formula (1) and general formula (2), n represents an integer of 1 to 12, m represents an integer of 1 to 12, X or Y represents a single bond, -COO, -OCO-, -N=N-, -C=C- or _-C6H4- , _W1 represents a cinnamoyl group, a chalcone group, a _{cinnamylidene} group, a biphenylacryloyl group, a furylacryloyl group, a naphthylacryloyl group and derivatives thereof, or -H, -OH and -CN, and _W2 represents a cinnamoyl group, a chalcone group, a cinnamylidene group, a biphenylacryloyl group, a furylacryloyl group, a naphthylacryloyl group and derivatives thereof, or -H, -OH and -CN.

Among the side chains represented by the above formula, monomers having side chains represented by -H, -OH, and -CN as _W1 and _W2 do not exhibit photosensitivity, but can be copolymerized with a monomer having a photosensitive group in the side chain to obtain a liquid crystal polymer having a photosensitive group. In the case of copolymerization, the higher the ratio of monomers not exhibiting photosensitivity represented by the above formula, the easier it is to obtain a polymer that is likely to be homeotropically aligned, but the copolymerization ratio can be appropriately set in consideration of the balance between homeotropic alignment and liquid crystallinity.

In general formula (3), s represents 0 or 1, t represents an integer from 1 to 3, and R represents H, an alkyl group, an alkyloxy group, or a halogen.

Alignment layers such as the positive C layer may contain additives such as light stabilizers and antioxidants to the extent that they do not impair the effects of the present invention.

The positive C layer can be formed, for example, by preparing a coating liquid for the positive C layer by dissolving or diluting the components constituting the positive C layer (e.g., a liquid crystalline polymer formed from monomer units having side chains represented by general formulas (1) to (3), and additives) in a solvent, and then coating and drying the coating liquid on a substrate.

Solvents for the coating solution for the positive C layer include dioxane, dichloroethane, cyclohexanone, toluene, tetrahydrofuran, o-dichlorobenzene, methyl ethyl ketone, methyl isobutyl ketone, etc., and these solvents are used alone or in combination.

In the process of applying the coating solution for the positive C layer onto the substrate and removing the solvent, the positive C layer begins to show homeotropic alignment, and the homeotropic alignment is enhanced by further heating after drying. Specifically, the homeotropic alignment is induced by heating to a temperature equal to or higher than the liquid crystal phase transition temperature and equal to or lower than the isotropic transition temperature (preferably lower than the isotropic transition temperature) and then cooling.
Furthermore, the homeotropically aligned layer is irradiated with linearly polarized ultraviolet light. By irradiating with linearly polarized ultraviolet light, the photoreaction of the photosensitive group of the liquid crystal polymer having a photosensitive group proceeds anisotropically, and the liquid crystal alignment ability to align the liquid crystal compound in the positive A layer is imparted. The wavelength of the irradiated light is preferably 200 nm to 500 nm, more preferably 250 nm to 400 nm. Even if such linearly polarized ultraviolet light is irradiated, the alignment of the homeotropic alignment layer is not substantially affected.

After irradiating the positive C layer with linearly polarized UV light and forming the positive A layer on the positive C layer, it is preferable to irradiate with non-polarized UV light. When irradiated with non-polarized UV light, dimerization of the liquid crystal polymer having a photosensitive group progresses, the orientation is fixed, and a stable homogeneous orientation layer is formed. Note that since the homeotropic orientation of the positive A layer is completed before irradiation with non-polarized UV light, it can be said that the homeotropic orientation of the positive A layer is not substantially disturbed by the non-polarized UV light. In addition, by irradiating with non-polarized UV light, the photosensitive group of the positive C layer and the photosensitive group of the positive A layer react with each other, and it is expected that the adhesion will be further improved.

The alignment layer such as the positive C layer preferably has an R th (550) of −100 nm to −50 nm, more preferably −90 nm to −60 nm. By setting the R th (550) of the alignment layer in this range, visibility in oblique directions can be easily improved.

It is preferable that the Re(550) of an alignment layer such as a positive C layer is small, preferably 20 nm or less, more preferably 10 nm or less, even more preferably 5 nm or less, and even more preferably 1 nm or less.

In this specification, the in-plane retardation, thickness retardation, haze and total light transmittance refer to the average value of the measured values at 16 points. The 16 measurement points are preferably centered on 16 intersections of lines drawn on the inner area of the margin, with a margin of 1 cm from the outer edge of the measurement sample, dividing the area inside the margin into 5 equal parts in the vertical and horizontal directions. When the measurement sample is a rectangle, it is preferable to measure the 16 intersections of lines drawn on the inner area of the margin, with a margin of 1 cm from the outer edge of the rectangle, and calculate the average value. In addition, when the measurement sample is a shape other than a rectangle, such as a circle, an ellipse, a triangle, or a pentagon, it is preferable to draw a rectangle with the maximum area inscribed in these shapes, and measure 16 points on the rectangle using the above method.
The in-plane retardation and the retardation in the thickness direction can be measured, for example, by using a product called "KOBRA-WR" manufactured by Oji Measurement Co., Ltd.

The thickness of an alignment layer such as a positive C layer is preferably from 100 nm to 5 μm, more preferably from 50 nm to 3 μm, and further preferably from 100 nm to 2 μm.
The thickness of each layer, such as the alignment layer such as the positive C layer, the positive A layer, and the substrate, can be calculated, for example, as the average value of 20 points by observing a cross-sectional image of the optical laminate with a scanning transmission electron microscope (STEM) or the like.

<Positive A layer>
The positive A layer is disposed in a position in the thickness direction of the optical laminate so as to be in contact with the positive C layer. The positive A layer contains a compound a.

Compound a contains an atom X that is not substantially contained in other compounds contained in the positive C layer. Examples of the atom X contained in compound a include a sulfur atom and a nitrogen atom, and a sulfur atom is preferable.
The positive A layer is preferably formed from a liquid crystal compound. The liquid crystal compound is preferably a polymerizable liquid crystal compound. That is, the compound a is preferably a liquid crystal compound, more preferably a polymerizable liquid crystal compound. In addition, the compound a is preferably a polymerizable liquid crystal compound containing a sulfur atom or a nitrogen atom as the atom X, more preferably a polymerizable liquid crystal compound containing a sulfur atom as the atom X.

The positive A layer is a layer that exhibits homogeneous alignment. Homogeneous alignment refers to a state in which the liquid crystal material is aligned parallel to the layer surface and in the same direction (optical uniaxiality). The liquid crystal compound that can be homogeneously aligned may be a material made of a liquid crystal polymer or a material made of a liquid crystal monomer.
As described above, when the homeotropically aligned positive C layer is irradiated with linearly polarized ultraviolet light, the photoreaction of the photosensitive group of the liquid crystal polymer having the photosensitive group proceeds anisotropically, and the liquid crystal alignment ability to align the liquid crystal compound of the positive A layer is imparted. Therefore, even if the coating liquid for the positive A layer is directly applied onto the positive C layer, dried and cured, a homogeneously aligned positive A layer can be obtained on the homeotropically aligned positive C layer.

The positive A layer preferably has Re(450), Re(550) and Re(650) satisfying the following relationship (i). That is, the positive A layer preferably has reverse dispersion. By using a positive A layer having reverse dispersion satisfying the following relationship (i), it is possible to easily impart reverse dispersion to the entire optical laminate including the positive A layer and the positive C layer, and it is possible to easily improve visibility and antireflection properties in wavelength ranges outside 550 nm.
Re(450)<Re(550)<Re(650) (i)

There are no particular limitations on the Re(450), Re(550), and Re(650) of the positive A layer, but if the positive A layer is a λ/4 retardation layer, it is preferable that they are in the following ranges, and if the positive A layer is a λ/2 retardation layer, they are in the following ranges.

<<In the case of λ/4 retardation layer>>
Re(450) is preferably 82 nm to 143 nm, more preferably 90 nm to 135 nm. Re(550) is preferably 100 nm to 175 nm, more preferably 110 nm to 165 nm. Re(650) is preferably 119 nm to 206 nm, more preferably 130 nm to 195 nm.
Moreover, the laminate of the positive A layer (λ/4 retardation layer) and the positive C layer preferably has an Rth(550) of −40 nm to 40 nm, more preferably −25 nm to 25 nm.

<<In the case of λ/2 retardation layer>>
Re(450) is preferably 165 nm to 286 nm, more preferably 180 nm to 270 nm. Re(550) is preferably 201 nm to 349 nm, more preferably 220 nm to 230 nm. Re(650) is preferably 237 nm to 412 nm, more preferably 260 nm to 390 nm.
Moreover, the laminate of the positive A layer (λ/2 retardation layer) and the positive C layer preferably has Rth(550) of −50 nm to 50 nm, more preferably −30 nm to 30 nm.

The thickness of the positive A layer is preferably 100 nm to 5 μm, more preferably 500 nm to 4 μm, and even more preferably 1.5 μm to 3.0 μm.

The reverse dispersion positive A layer can be formed from a liquid crystal compound exhibiting reverse dispersion, and such a liquid crystal compound is preferably polymerizable.
Examples of the polymerizable liquid crystal compound exhibiting reverse dispersion include those represented by general formula (1) in JP-A-2019-73712 and those represented by general formula (II) in International Publication No. WO2017/043438.

Specific examples of the polymerizable liquid crystal compound exhibiting reverse dispersion include the compounds represented by the following chemical formulas (4) to (29). All of the compounds represented by the following chemical formulas (4) to (29) contain a sulfur atom and a nitrogen atom in the molecule.
The compounds represented by the following chemical formulas (4) to (29) have a structure in which the left and right sides of the molecular structure are easily movable with the biphenyl group at the center, and are therefore preferred in that they easily permeate into the alignment film and the average detectable amount of atom X in the alignment film can be easily adjusted to the above-mentioned range.

The positive A layer may contain additives such as light stabilizers and antioxidants to the extent that they do not impair the effects of the present invention.

The positive A layer can be formed, for example, by preparing a coating liquid for the positive A layer by dissolving or diluting the components constituting the positive A layer in a solvent, coating the coating liquid on the positive C layer, drying it, and curing it by irradiating it with ionizing radiation as necessary.

Examples of solvents for the coating solution for the positive A layer include ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc.), ethers (dioxane, tetrahydrofuran, 1,3-dioxolane, etc.), aliphatic hydrocarbons (hexane, etc.), alicyclic hydrocarbons (cyclohexane, etc.), aromatic hydrocarbons (toluene, xylene, etc.), halogenated carbons (dichloromethane, dichloroethane, etc.), esters (methyl acetate, ethyl acetate, butyl acetate, etc.), alcohols (isopropanol, butanol, cyclohexanol, etc.), cellosolves (methyl cellosolve, ethyl cellosolve, etc.), glycol ethers (propylene glycol monomethyl ether acetate, etc.), cellosolve acetates, sulfoxides (dimethyl sulfoxide, etc.), amides (dimethylformamide, dimethylacetamide, etc.), and mixtures of these may also be used.

Among the above solvents, it is preferable to use methyl isobutyl ketone, cyclohexanone, 1,3-dioxolane, toluene, etc., and it is more preferable to use cyclohexanone and 1,3-dioxolane, which have high polarity and easily penetrate into the alignment layer.

The proportion of solvent in the coating solution for the positive A layer is preferably 70% to 95% by mass, and more preferably 75% to 90% by mass.

<Substrate>
The optical laminate may have a substrate.
The substrate is preferably a plastic film.
Examples of polymers constituting the plastic film include cellulose acylate, polycarbonate-based polymers, polyester-based polymers such as polyethylene terephthalate and polyethylene naphthalate, acrylic-based polymers such as polymethyl methacrylate, styrene-based polymers such as polystyrene and acrylonitrile-styrene copolymers (AS resins), polyolefin-based polymers such as polyethylene, polypropylene and ethylene-propylene copolymers, vinyl chloride-based polymers, amide-based polymers such as nylon and aromatic polyamide, imide-based polymers, sulfone-based polymers, polyethersulfone-based polymers, polyetheretherketone-based polymers, polyphenylene sulfide-based polymers, vinylidene chloride-based polymers, vinyl alcohol-based polymers, vinyl butyral-based polymers, arylate-based polymers, polyoxymethylene-based polymers, and epoxy-based polymers.

Considering the need to make the image display device thinner, the substrate is preferably one from which the alignment layer and the positive A layer can be peeled off. By using a peelable substrate, the alignment layer and the positive A layer can be transferred to other members of the image display device.
The optical laminate of the present invention has good adhesion between the alignment layer and the positive A layer, and therefore peeling at the interface between the alignment layer and the positive A layer due to stress generated during transfer can be suppressed, making it preferable in that a peelable substrate can be easily used.
The peelable substrate may be, for example, the above-mentioned plastic film itself, or the above-mentioned plastic film whose surface has been subjected to a release treatment with a general-purpose release agent or the like.

The thickness of the substrate is usually about 25 μm to 150 μm, preferably 30 μm to 125 μm, and more preferably 40 μm to 100 μm.

<Other demographics>
The optical laminate may have other layers, such as a gas barrier layer, an adhesive layer, and a retardation layer, as long as the effects of the present invention are not impaired.

<Physical Properties of Optical Laminate>
The optical laminate of the present invention preferably satisfies the relationship of the following formula (A) when the in-plane retardation of the optical laminate at a wavelength of 450 nm is defined as Re(450), the in-plane retardation of the optical laminate at a wavelength of 550 nm is defined as Re(550), and the in-plane retardation of the optical laminate at a wavelength of 650 nm is defined as Re(650).
Re(450)<Re(550)<Re(650) (A)

By satisfying formula (A), the optical laminate as a whole will exhibit reverse wavelength dispersion characteristics, making it easier to improve visibility and anti-reflection properties in wavelength ranges outside 550 nm.

The optical laminate preferably has a haze according to JIS K7136:2000 of 1.0% or less, more preferably 0.9% or less, and even more preferably 0.8% or less.
Furthermore, the optical laminate preferably has a total light transmittance according to JIS K7361-1:1997 of 80% or more, more preferably 85% or more, and even more preferably 90% or more.

The total thickness of the optical laminate is not particularly limited, but from the viewpoint of improving handleability and mechanical strength, it is preferably 15 μm to 300 μm, more preferably 20 μm to 200 μm, and even more preferably 25 μm to 100 μm.

<Size, shape, etc.>
The optical laminate may be in the form of a sheet or a roll.
The size of the sheet is not particularly limited, but generally, the size is about 2 inches to 500 inches diagonally. The width and length of the roll are not particularly limited, but generally, the width is about 500 mm to 3000 mm, and the length is about 500 m to 5000 m.
The shape of the sheets is not particularly limited either, and may be, for example, polygonal (triangle, square, pentagon, etc.) or circular, or may be a random, indeterminate shape.

[Polarizer]
The polarizing plate of the present invention has a polarizer, a transparent protective plate A arranged on one side of the polarizer, and a transparent protective plate B arranged on the other side of the polarizer, and either the transparent protective plate A or the transparent protective plate B is the optical laminate of the present invention described above.

FIG. 2 is a cross-sectional view showing an embodiment of the polarizing plate of the present invention.
The polarizing plate 200 in Fig. 2 includes a polarizer 50, a transparent protective plate A (61) disposed on one side of the polarizer, and a transparent protective plate B (62) disposed on the other side of the polarizer. The transparent protective plate A (61) in Fig. 2 is an optical laminate 100.

<Polarizer>
Examples of polarizers include sheet-type polarizers such as polyvinyl alcohol films, polyvinyl formal films, polyvinyl acetal films, and saponified ethylene-vinyl acetate copolymer films dyed with iodine or the like and stretched, wire-grid-type polarizers made of a large number of metal wires arranged in parallel, coating-type polarizers coated with lyotropic liquid crystal or a dichroic guest-host material, and multilayer thin-film-type polarizers. These polarizers may be reflective polarizers that have a function of reflecting polarized components that are not transmitted.

<Transparent protective plate>
On one side of the polarizer, a transparent protective plate A is disposed, and on the other side, a transparent protective plate B. One of the transparent protective plate A and the transparent protective plate B is the above-mentioned optical laminate of the present invention.

Examples of the transparent protective plate A and the transparent protective plate B other than the optical laminate include plastic films and glass. Examples of the plastic film include polyester films, polycarbonate films, cycloolefin polymer films, and acrylic films, and from the viewpoint of mechanical strength, stretched films of these films are preferred. Examples of the glass include alkali glass, nitride glass, soda-lime glass, borosilicate glass, and lead glass. In addition, it is preferable that the glass as the transparent protective plate for protecting the polarizer is also used as other members of the image display device (for example, the glass substrate of the liquid crystal display element, the front panel of the image display device).
The polarizer and the transparent protective plate are preferably attached to each other via an adhesive. A general-purpose adhesive can be used as the adhesive, and a PVA-based adhesive is preferable.

The polarizing plate of the present invention is preferably used as a polarizing plate arranged on the light exit surface side of a display element. When used as described above, it is preferable that the transparent protective plate on the light incident surface side based on the polarizer is the optical laminate of the present invention described above. From the viewpoint of making the polarizing plate function as a circular polarizing plate, the orientation of the slow axis of the positive A layer relative to the absorption axis of the polarizer is preferably in the range of 30° to 60°, and more preferably in the range of 40° to 50°.

[Display panel]
The display panel of the present invention comprises the above-mentioned optical layered body of the present invention disposed on the light-emitting surface side of a display element.

Figure 3 is a cross-sectional view showing an embodiment of a display panel 500 of the present invention. The display panel 500 in Figure 3 has an optical laminate 100 laminated on the light-emitting surface side of the display element 300.

When the display element of the display panel is a liquid crystal display element, a backlight (not shown) is required on the rear side of the liquid crystal display element. Either an edge-lit backlight or a direct-type backlight can be used as the backlight. In addition, examples of light sources for the backlight include LEDs and CCFLs, but a backlight using quantum dots as the light source is preferable because it is easy to improve color reproducibility.

It is preferable that the display panel has a polarizer on the surface of the optical laminate opposite the display element. By adopting such a configuration, it is possible to provide the image display device with an anti-reflection function for external light and to suppress loss of color when viewed from an oblique angle.

<Display element>
Examples of the display element include a liquid crystal display element, an organic EL display element, an inorganic EL display element, a plasma display element, an electronic paper display element, an LED display element (such as a micro LED), a display element using quantum dots, etc. These display elements may have a touch panel function inside the display element.

[Image display device]
The image display device of the present invention is not particularly limited as long as it is equipped with the display panel of the present invention, but it preferably comprises the display panel of the present invention, a drive control unit electrically connected to the display panel, and a housing that accommodates these.

The image display device may be a foldable image display device or a rollable image display device. The image display device may also be an image display device with a touch panel.

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Note that "parts" and "%" are based on mass unless otherwise specified.

The optical laminates obtained in the examples and comparative examples were subjected to the following measurements and evaluations. The results are shown in Table 1.

1-1. Measurement of sulfur atoms Cut samples were prepared by cutting the optical laminates of the examples and comparative examples to a predetermined size, and embedded samples were prepared by embedding the cut samples in epoxy resin. Next, 20 pieces of each thin measurement sample (thickness 0.08 μm) were prepared by cutting the embedded samples vertically with a diamond knife.
Next, the mass-based detection amount of sulfur atoms in the positive A layer and the alignment layer of the measurement sample was measured by scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX). Based on the measurement results, the average detection amount of X atoms in the alignment layer (positive C layer) was calculated when the average detection amount of sulfur atoms in the positive A layer was normalized to 100 by mass, and the average value of 20 samples was calculated. The results are shown in Table 1.
Furthermore, based on the above measurement results, the "coefficient of variation under condition 1" and the "ratio under condition 2" in the specification were calculated. The results are shown in Table 1.
The SEM-EDX measuring devices used were SEM "SU8000" manufactured by Hitachi High-Technologies Corporation and EDX "XMAX80" manufactured by Oxford Instruments. The measuring conditions for the devices were set as follows:
<Measurement conditions>
The characteristic X-ray spectrum was obtained by adjusting the irradiation current and measurement time appropriately so that the target elements could be sufficiently detected, with an acceleration voltage of 30 kV and a focal length of 15 mm (sample tilt of 0 degrees). The concentration of each element was calculated by the ZAF correction method (a method of calculating the content of each element by applying atomic number correction Z, absorption correction A, and fluorescence correction F to the relative intensity of each element).

1-2. Adhesion The intermediates of the optical laminates of the Examples and Comparative Examples were stored for 24 hours under an environment of 23°C and 50% relative humidity, and then the alignment layer (positive C layer) and the positive A layer of the intermediates of the optical laminates of the Examples and Comparative Examples were transferred to glass with an adhesive layer to form a glass laminate, and a blade was inserted from the alignment layer (positive C layer) side of the glass laminate to cross-cut into a grid of 100 squares (10 squares vertically x 10 squares horizontally) so that the tip of the blade reached the adhesive layer. Two types of grid cut intervals, 1 mm and 2 mm, were prepared.
An adhesive tape (manufactured by Nichiban Co., Ltd., product name "3M Scotch Removable Tape, CAT. NO. 811-3-18) was applied to the cross-cut surface of the cross-cut sample, and a peel test was performed in accordance with the cross-cut method specified in JIS K5600-5-6:1999. For each cut interval of 1 mm and 2 mm, the number of peeled meshes was evaluated using a microscope (Keyence Corporation's digital microscope VH5500, set magnification 100 times). The results are shown in Table 1. Note that "0/100" indicates that the number of peeled meshes is 0, and the adhesion between the alignment layer (positive C layer) and the positive A layer is the best, and "100/100" indicates that all meshes have peeled off, and the adhesion between the alignment layer (positive C layer) and the positive A layer is poor.

1-3. Transferability The optical laminates of the Examples and Comparative Examples (laminates in which the alignment layer (positive C layer) and positive A layer of the intermediates of the optical laminates of the Examples and Comparative Examples were transferred to glass) were evaluated using a microscope (Keyence Corporation digital microscope VH5500, set magnification 100x) to see whether peeling occurred at the interface between the positive A layer and the positive C layer. Those in which peeling was not observed were rated "A," and those in which peeling was observed were rated "C." The results are shown in Table 1.

2. Synthesis of compounds for alignment layer 2-1. Synthesis of compounds used in the examples (monomer 1)
4-Hydroxy-4'-hydroxyethoxybiphenyl was synthesized by heating 4,4'-biphenyldiol and 2-chloroethanol under alkaline conditions. This product was reacted with 1,6-dibromohexane under alkaline conditions to synthesize 4-(6-bromohexyloxy)-4'-hydroxyethoxybiphenyl. Then, lithium methacrylate was reacted to synthesize Monomer 1 represented by the following chemical formula (30).

(Monomer 2)
Cinnamoyl chloride was added to Monomer 1 under basic conditions to synthesize Monomer 2 represented by the following chemical formula (31).

(Polymer 1)
Monomer 1 and monomer 2 were dissolved in tetrahydrofuran in a molar ratio of 3:7, and AIBN (azobisisobutyronitrile) was added as a reaction initiator, followed by polymerization at 70° C. for 24 hours to obtain a photosensitive polymer 1. This polymer 1 exhibited liquid crystallinity.

2-2. Preparation of Compounds Used in Comparative Examples For the alignment film of the comparative examples, an alignment film-forming composition containing a polycinnamate compound was used.

3. Synthesis of Compound for Positive A Layer According to the description of Production Example 10 in the Examples of JP-A-2019-73712, the following compound a containing a sulfur atom (compound represented by chemical formula (5)) was synthesized.

4. Preparation of optical laminate [Example 1]
The polymer 1 obtained in 2-1 above was dissolved in cyclohexanone, and a photopolymerization initiator (4,4'-bis(diethylamino)benzophenone from Tokyo Chemical Industry Co., Ltd.) was added to prepare a coating solution for a positive C layer 1. The content of the photopolymerization initiator in the coating solution for a positive C layer 1 was 2 parts by weight per 100 parts by weight of the polymer 1.
On a substrate (a 100 μm-thick polyethylene terephthalate (PET) film, product name "A4100", Toyobo Co., Ltd.), the coating solution 1 for the positive C layer was applied to a thickness of 0.6 μm using a Mayer bar, and dried at room temperature (about 25° C.). Next, the coating solution was heated to 130° C. and then cooled to form a positive C layer, which is a homeotropic alignment layer. The Re(550) of the positive C layer was 3.2 nm, and the Rth(550) was −73 nm.
Next, the positive C layer was irradiated with linearly polarized ultraviolet light (ultraviolet light obtained by linearly polarizing light obtained by passing light from a high-pressure mercury lamp through a Glan-Teller prism) for 15 seconds, thereby causing the photoreaction of the photosensitive group of polymer 1 to proceed anisotropically.
Next, the following coating solution 1 for positive A layer was applied onto the positive C layer so that the thickness after curing was 2 μm, forming a film. After that, it was dried at 120° C. for 60 seconds, and then irradiated with ultraviolet light (non-polarized ultraviolet light) at an irradiation dose of 400 mJ/cm ² using an H bulb manufactured by Fusion, to form a positive A layer, and an intermediate of the optical laminate of Example 1 was obtained. The Re(550) of the positive A layer was 161 nm, and the Rth(550) of the laminate was −5 nm.
Next, a transparent adhesive layer (manufactured by PANAC, product name: Panaclean PD-S1, thickness 25 μm) was formed on the glass substrate, and the surface of the positive A layer side of the optical laminate of the examples and comparative examples was attached to the transparent adhesive layer. Next, the peelable substrate (PET film) was peeled off to obtain the optical laminate of Example 1 having the glass substrate, the transparent adhesive layer, the positive A layer, and the positive C layer in this order. The optical laminate had Re(450) of 136 nm, Re(550) of 161 nm, Re(650) of 164 nm, and Rth(550) of -5 nm.

<Positive A layer coating solution 1>
100 parts by mass of the compound a containing a sulfur atom obtained in 3 above; 4 parts by mass of a photopolymerization initiator (2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, IGM Resins BV, product name "Omnirad 907")
Toluene 70 parts by weight Cyclohexanone 30 parts by weight

[Comparative Example 1]
An optical laminate of Comparative Example 1 was obtained in the same manner as in Example 1, except that the coating solution 1 for the positive C layer was changed to the following coating solution 2 for the positive C layer. The positive C layer of Comparative Example 1 had an Re(550) of 0.5 nm and an Rth(550) of −0.2 nm.

<Positive C layer coating solution 2>
Polymerizable liquid crystal compound: 4 parts by weight (polycinnamate compound)
Propylene glycol monomethyl ether 96 parts by mass

The results of the examples confirm that the optical laminate of the examples can contribute to a thinner product because the alignment layer and the positive A layer are directly laminated together, and that the alignment layer and the positive A layer have excellent adhesion to each other.

10: Substrate 20: Orientation layer 30: Positive A layer 50: Polarizer 61: Transparent protective plate A
62: Protective protective plate B
100: Optical laminate 200: Polarizing plate 300: Display element 500: Display panel

Claims (11)

An optical stack having an orientation layer and a positive A layer,
the alignment layer and the positive A layer are in contact with each other,
The positive A layer contains compound a,
the alignment layer contains the compound a transferred from the positive A layer and other compounds,
The compound a contains an atom X that is not substantially contained in the other compounds,
When the average detectable amount of the atom X in the positive A layer is normalized to 100 on a mass basis, the average detectable amount of the atom X in the alignment layer is 23 or more and 50 or less;
An optical laminate , wherein the amount of the atom X detected in the alignment layer satisfies the following condition 1 .
(Condition 1)
The amount of the atom X in the alignment layer is detected at 100 points every 26 nm in a direction parallel to the interface at a position 200 nm in the thickness direction from the interface between the alignment layer and the positive A layer. The mass-based coefficient of variation of the amount of the atom X detected at the 100 points is 0.16 or more. An optical stack having an orientation layer and a positive A layer,
the alignment layer and the positive A layer are in contact with each other,
The positive A layer contains compound a,
the alignment layer contains the compound a transferred from the positive A layer and other compounds,
The compound a contains an atom X that is not substantially contained in the other compounds,
When the average detectable amount of the atom X in the positive A layer is normalized to 100 on a mass basis, the average detectable amount of the atom X in the alignment layer is 23 or more and 50 or less;
An optical laminate, wherein the amount of the atom X detected in the positive A layer and the alignment layer satisfies the following condition 2.
(Condition 2)
The amount of the atom X in the positive A layer is detected at 100 points every 26 nm in a direction parallel to the interface at a position 200 nm in the thickness direction from the interface between the positive A layer and the alignment layer. The mass-based coefficient of variation of the detected atom X is defined as CV1.
The amount of the atom X in the alignment layer is detected at 100 points every 26 nm in a direction parallel to the interface at a position 200 nm in the thickness direction from the interface between the alignment layer and the positive A layer. The mass-based coefficient of variation of the detected atom X is defined as CV2.
The ratio of the CV1 to the CV2 (CV2/CV1) is 2.00 or more. The optical laminate according to claim 1 or 2 , wherein the atom X is a sulfur atom. 4. The optical laminate according to claim 1 , wherein the compound a is a polymerizable liquid crystal compound containing a sulfur atom as the atom X. The optical laminate according to any one of claims 1 to 4 , wherein the alignment layer is a positive C layer. The optical laminate according to any one of claims 1 to 5 , wherein the other compounds include a liquid crystal compound having a photosensitive group. 7. The optical laminate according to claim 1 , wherein, when the retardation in the thickness direction of the alignment layer at a wavelength of 550 nm is defined as Rth(550), Rth(550) is −100 nm to −50 nm. The optical laminate according to any one of claims 1 to 7, wherein the in-plane retardation of the optical laminate at a wavelength of 450 nm is defined as Re(450), the in-plane retardation of the optical laminate at a wavelength of 550 nm is defined as Re(550), and the in-plane retardation of the optical laminate at a wavelength of 650 nm is defined as Re( 650 ), and the relationship of the following formula (A) is satisfied.
Re(450)<Re(550)<Re(650) (A) A polarizing plate having a polarizer, a transparent protective plate A arranged on one side of the polarizer, and a transparent protective plate B arranged on the other side of the polarizer, wherein either the transparent protective plate A or the transparent protective plate B is an optical laminate according to any one of claims 1 to 8 . A display panel comprising the optical laminate according to any one of claims 1 to 8 disposed on a light exit surface of a display element. An image display device comprising the display panel according to claim 10 .